Increasingly, your personal email communications are not as private as you might believe. Employers, high-tech criminals, spammers, ISPs, governments, surveillance agencies and identity thieves are just a few of the people who might routinely be intercepting and reading your mail without your consent or knowledge.
You lock your home and put letters in envelopes not only to protect the valuables inside, but also because you value your privacy itself. You need to protect your Internet communications for the same reason.
In some professions, ensuring the privacy of communications with customers is a matter of basic respect for a customer's right to privacy. In some instances, such as with personal medical, legal or financial information, laws in various countries require that professionals communicating with customers over email do so using high-quality encryption.